1. Field
This invention relates to hand guns, notably automatic pistols, and provides an improved mechanism for positively securing the barrel of an automatic pistol to its frame in a detachable manner.
2. State of the Art
Hand guns such as automatic pistols with detachable barrels are well known. A principal problem encountered with such guns is misalignment of the barrel upon the frame, particularly after extensive usage. It is of course desirable for the barrel-mounting means to facilitate installation and removal, even by one who is unskilled, so as to enable interchanging of barrels without special tools. Many of the firearms of this type known to the prior art have insufficient rigidity of support for the barrel upon the frame, and thus fail to secure proper alignment after continuous operation without adjustment. Moreover, it has been found that after prolonged use, wear of parts effects a loosening of the barrel on the frame thereby contributing to misalignment after extensive usage.
An example of a high quality firearm with a detacbable barrel is that described in U.S. Pat. No. 3,150,458. The automatic piston therein disclosed has a frame and a barrel, each of which has longitudinally extending interfitting portions in cooperative engagement for supporting the barrel in longitudinal alignment on the frame. The barrel is held to the frame with positive retention means including a screw which is inserted through a bore in the frame to threadedly engage a lug depending from the barrel into a recess in the frame. The lug further carries a transverse pin with end portions which engage a groove in the frame so that as the screw is threaded into the lug the barrel is urged down and forward on the frame. Although this action permits adjustment of the barrel to maintain seating of the barrel on the frame after use, movement of the barrel downward automatically results in a slight forward movement of the barrel with respect to the receiver and slide of the firearm. The bolt of the pistol moves forward to maintain a proper seal at the breech, but provision must be made at the time of manufacture to avoid mismating or misalignment of parts as a consequence.
A more recent example of a detachable barrel mounting system in an automatic pistol is that of the "High Standard" target pistols produced by the Leisure Group, Inc., 1817 Dixwell Avenue, Hamden, Connecticut, wherein the barrel is provided with a depending cylindrical leg which is inserted through a matching cylindrical bore milled vertically through the surface of the frame upon which the bottom side of the barrel is intended to seat. The leg is inserted through a bore in a spring-biased plunger carrying a ramped slot which in turn engages a milled surface in the depending leg. In this fashion the barrel is continuously urged down toward the seating surfaces of the frame by spring pressure upon the cylindrical member. This arrangement provides for quick assembly and take-down of the pistol, and it maintains the longitudinal position of the barrel with respect to the frame, assuming the tolerances of the leg and bore are held sufficiently close. This structure imposes high tolerance requirements on the manufacturer, however. Moreover, the tendency of the spring pressure arrangement is to urge the barrel not only down but forward with respect to the frame. Thus, any wear on the attachment surfaces will be taken up by slight movement of the barrel forward away from the breech.
There remains a need in the art for a rapid attachment system to secure the barrel of an automatic pistol to its frame in a fashion which minimizes the opportunity for loosening either initially or after prolonged usage of the firearm. There is further a need for such a system with decreased tolerance requirements at the point of manufacture.